// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: value }(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// SPDX-License-Identifier: MIT
pragma solidity 0.7.6;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";


/**
 * @dev Interface extending ERC20 standard to include decimals() as
 *      it is optional in the OpenZeppelin IERC20 interface.
 */
interface IERC20Ext is IERC20 {
    /**
     * @dev This function is required as Kyber requires to interact
     *      with token.decimals() with many of its operations.
     */
    function decimals() external view returns (uint8 digits);
}

// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.7.6;


import {IERC20Ext} from '@kyber.network/utils-sc/contracts/IERC20Ext.sol';

interface IPool {

  event AuthorizedStrategy(address indexed strategy);
  event UnauthorizedStrategy(address indexed strategy);
  event Paused(address indexed sender);
  event Unpaused(address indexed sender);
  event WithdrawToken(
    IERC20Ext indexed token,
    address indexed sender,
    address indexed recipient,
    uint256 amount
  );

  function pause() external;
  function unpause() external;
  function authorizeStrategies(address[] calldata strategies) external;
  function unauthorizeStrategies(address[] calldata strategies) external;
  function withdrawFunds(
    IERC20Ext[] calldata tokens,
    uint256[] calldata amounts,
    address payable recipient
  ) external;
  function isPaused() external view returns (bool);
  function isAuthorizedStrategy(address strategy) external view returns (bool);
  function getAuthorizedStrategiesLength() external view returns (uint256);
  function getAuthorizedStrategyAt(uint256 index) external view returns (address);
  function getAllAuthorizedStrategies()
    external view returns (address[] memory strategies);
}

// SPDX-License-Identifier: MIT
pragma solidity 0.7.6;

import {IERC20Ext} from '@kyber.network/utils-sc/contracts/IERC20Ext.sol';


interface IRewardsDistributor {
  event Claimed(
    uint256 indexed cycle,
    address indexed user,
    IERC20Ext[] tokens,
    uint256[] claimAmounts
  );

  /**
   * @dev Claim accumulated rewards for a set of tokens at a given cycle number
   * @param cycle cycle number
   * @param index user reward info index in the array of reward info
   * during merkle tree generation
   * @param user wallet address of reward beneficiary
   * @param tokens array of tokens claimable by reward beneficiary
   * @param cumulativeAmounts cumulative token amounts claimable by reward beneficiary
   * @param merkleProof merkle proof of claim
   * @return claimAmounts actual claimed token amounts sent to the reward beneficiary
   **/
  function claim(
    uint256 cycle,
    uint256 index,
    address user,
    IERC20Ext[] calldata tokens,
    uint256[] calldata cumulativeAmounts,
    bytes32[] calldata merkleProof
  ) external returns (uint256[] memory claimAmounts);

  /**
   * @dev Checks whether a claim is valid or not
   * @param cycle cycle number
   * @param index user reward info index in the array of reward info
   * during merkle tree generation
   * @param user wallet address of reward beneficiary
   * @param tokens array of tokens claimable by reward beneficiary
   * @param cumulativeAmounts cumulative token amounts claimable by reward beneficiary
   * @param merkleProof merkle proof of claim
   * @return true if valid claim, false otherwise
   **/
  function isValidClaim(
    uint256 cycle,
    uint256 index,
    address user,
    IERC20Ext[] calldata tokens,
    uint256[] calldata cumulativeAmounts,
    bytes32[] calldata merkleProof
  ) external view returns (bool);

  /**
   * @dev Fetch accumulated claimed rewards for a set of tokens since the first cycle
   * @param user wallet address of reward beneficiary
   * @param tokens array of tokens claimed by reward beneficiary
   * @return userClaimedAmounts claimed token amounts by reward beneficiary since the first cycle
   **/
  function getClaimedAmounts(address user, IERC20Ext[] calldata tokens)
    external
    view
    returns (uint256[] memory userClaimedAmounts);
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

/**
 * @dev These functions deal with verification of Merkle trees (hash trees),
 */
library MerkleProof {
    /**
     * @dev Returns true if a `leaf` can be proved to be a part of a Merkle tree
     * defined by `root`. For this, a `proof` must be provided, containing
     * sibling hashes on the branch from the leaf to the root of the tree. Each
     * pair of leaves and each pair of pre-images are assumed to be sorted.
     */
    function verify(bytes32[] memory proof, bytes32 root, bytes32 leaf) internal pure returns (bool) {
        bytes32 computedHash = leaf;

        for (uint256 i = 0; i < proof.length; i++) {
            bytes32 proofElement = proof[i];

            if (computedHash <= proofElement) {
                // Hash(current computed hash + current element of the proof)
                computedHash = keccak256(abi.encodePacked(computedHash, proofElement));
            } else {
                // Hash(current element of the proof + current computed hash)
                computedHash = keccak256(abi.encodePacked(proofElement, computedHash));
            }
        }

        // Check if the computed hash (root) is equal to the provided root
        return computedHash == root;
    }
}

// SPDX-License-Identifier: MIT
pragma solidity 0.7.6;


abstract contract PermissionAdmin {
    address public admin;
    address public pendingAdmin;

    event AdminClaimed(address newAdmin, address previousAdmin);

    event TransferAdminPending(address pendingAdmin);

    constructor(address _admin) {
        require(_admin != address(0), "admin 0");
        admin = _admin;
    }

    modifier onlyAdmin() {
        require(msg.sender == admin, "only admin");
        _;
    }

    /**
     * @dev Allows the current admin to set the pendingAdmin address.
     * @param newAdmin The address to transfer ownership to.
     */
    function transferAdmin(address newAdmin) public onlyAdmin {
        require(newAdmin != address(0), "new admin 0");
        emit TransferAdminPending(newAdmin);
        pendingAdmin = newAdmin;
    }

    /**
     * @dev Allows the current admin to set the admin in one tx. Useful initial deployment.
     * @param newAdmin The address to transfer ownership to.
     */
    function transferAdminQuickly(address newAdmin) public onlyAdmin {
        require(newAdmin != address(0), "admin 0");
        emit TransferAdminPending(newAdmin);
        emit AdminClaimed(newAdmin, admin);
        admin = newAdmin;
    }

    /**
     * @dev Allows the pendingAdmin address to finalize the change admin process.
     */
    function claimAdmin() public {
        require(pendingAdmin == msg.sender, "not pending");
        emit AdminClaimed(pendingAdmin, admin);
        admin = pendingAdmin;
        pendingAdmin = address(0);
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;

    uint256 private _status;

    constructor () {
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and make it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

        // Any calls to nonReentrant after this point will fail
        _status = _ENTERED;

        _;

        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = _NOT_ENTERED;
    }
}

// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.7.6;
pragma abicoder v2;

import {ReentrancyGuard} from '@openzeppelin/contracts/utils/ReentrancyGuard.sol';
import {SafeMath} from '@openzeppelin/contracts/math/SafeMath.sol';
import {SafeERC20} from '@openzeppelin/contracts/token/ERC20/SafeERC20.sol';
import {MerkleProof} from '@openzeppelin/contracts/cryptography/MerkleProof.sol';
import {Utils} from '@kyber.network/utils-sc/contracts/Utils.sol';
import {PermissionAdmin} from '@kyber.network/utils-sc/contracts/PermissionAdmin.sol';
import {IPool} from '../interfaces/liquidation/IPool.sol';
import {IERC20Ext, IRewardsDistributor} from '../interfaces/rewardDistribution/IRewardsDistributor.sol';


/**
 * @title Rewards Distributor contract for Kyber 3.0
 * - For users to claim allocated rewards for various KyberDAO program initiatives
 * (Eg. liquidity mining, staking rewards etc) in multiple tokens
 * Reward amounts for each user are generated off-chain and merklized by the Kyber team.
 * The admin (presumably the daoOperator) updates the reward amounts by submitting
 * the merkle root of a new cycle.
 **/
contract RewardsDistributor is IRewardsDistributor, PermissionAdmin, ReentrancyGuard, Utils {
  using SafeERC20 for IERC20Ext;
  using SafeMath for uint256;

  struct MerkleData {
    uint256 cycle;
    bytes32 root;
    string contentHash;
  }

  MerkleData private merkleData;
  // wallet => token => claimedAmount
  mapping(address => mapping(IERC20Ext => uint256)) public claimedAmounts;

  event RootUpdated(uint256 indexed cycle, bytes32 root, string contentHash);

  constructor(address admin) PermissionAdmin(admin) {}

  receive() external payable {}

  function getMerkleData() external view returns (MerkleData memory) {
    return merkleData;
  }

  /** 
   * @dev Claim accumulated rewards for a set of tokens at a given cycle number
   * @param cycle cycle number
   * @param index user reward info index in the array of reward info
   * during merkle tree generation
   * @param user wallet address of reward beneficiary
   * @param tokens array of tokens claimable by reward beneficiary
   * @param cumulativeAmounts cumulative token amounts claimable by reward beneficiary
   * @param merkleProof merkle proof of claim
   * @return claimAmounts actual claimed token amounts sent to the reward beneficiary
   **/
  function claim(
    uint256 cycle,
    uint256 index,
    address user,
    IERC20Ext[] calldata tokens,
    uint256[] calldata cumulativeAmounts,
    bytes32[] calldata merkleProof
  ) external override nonReentrant returns (uint256[] memory claimAmounts) {
    // verify if can claim
    require(
      isValidClaim(cycle, index, user, tokens, cumulativeAmounts, merkleProof),
      'invalid claim data'
    );


    claimAmounts = new uint256[](tokens.length);

    // claim each token
    for (uint256 i = 0; i < tokens.length; i++) {
      // if none claimable, skip
      if (cumulativeAmounts[i] == 0) continue;

      uint256 claimable = cumulativeAmounts[i].sub(claimedAmounts[user][tokens[i]]);
      if (claimable == 0) continue;

      claimedAmounts[user][tokens[i]] = cumulativeAmounts[i];
      claimAmounts[i] = claimable;
      if (tokens[i] == ETH_TOKEN_ADDRESS) {
        (bool success, ) = user.call{value: claimable}('');
        require(success, 'eth transfer failed');
      } else {
        tokens[i].safeTransfer(user, claimable);
      }
    }
    emit Claimed(cycle, user, tokens, claimAmounts);
  }

  /// @notice Propose a new root and content hash, only by admin
  function proposeRoot(
    uint256 cycle,
    bytes32 root,
    string calldata contentHash
  ) external onlyAdmin {
    require(cycle == merkleData.cycle.add(1), 'incorrect cycle');

    merkleData.cycle = cycle;
    merkleData.root = root;
    merkleData.contentHash = contentHash;

    emit RootUpdated(cycle, root, contentHash);
  }

  function pullFundsFromTreasury(
    IPool treasuryPool,
    IERC20Ext[] calldata tokens,
    uint256[] calldata amounts
  )
    external
    onlyAdmin
  {
    treasuryPool.withdrawFunds(tokens, amounts, payable(address(this)));
  }

   /**
   * @dev Checks whether a claim is valid or not
   * @param cycle cycle number
   * @param index user reward info index in the array of reward info
   * during merkle tree generation
   * @param user wallet address of reward beneficiary
   * @param tokens array of tokens claimable by reward beneficiary
   * @param cumulativeAmounts cumulative token amounts claimable by reward beneficiary
   * @param merkleProof merkle proof of claim
   * @return true if valid claim, false otherwise
   **/
  function isValidClaim(
    uint256 cycle,
    uint256 index,
    address user,
    IERC20Ext[] calldata tokens,
    uint256[] calldata cumulativeAmounts,
    bytes32[] calldata merkleProof
  ) public view override returns (bool) {
    if (cycle != merkleData.cycle) return false;
    if (tokens.length != cumulativeAmounts.length) return false;
    bytes32 node = keccak256(abi.encode(cycle, index, user, tokens, cumulativeAmounts));
    return MerkleProof.verify(merkleProof, merkleData.root, node);
  }

  /** 
   * @dev Fetch accumulated claimed rewards for a set of tokens since the first cycle
   * @param user wallet address of reward beneficiary
   * @param tokens array of tokens claimed by reward beneficiary
   * @return userClaimedAmounts claimed token amounts by reward beneficiary since the first cycle
   **/
  function getClaimedAmounts(address user, IERC20Ext[] calldata tokens)
    public
    view
    override
    returns (uint256[] memory userClaimedAmounts)
  {
    userClaimedAmounts = new uint256[](tokens.length);
    for (uint256 i = 0; i < tokens.length; i++) {
      userClaimedAmounts[i] = claimedAmounts[user][tokens[i]];
    }
  }

  function encodeClaim(
    uint256 cycle,
    uint256 index,
    address account,
    IERC20Ext[] calldata tokens,
    uint256[] calldata cumulativeAmounts
  ) external pure returns (bytes memory encodedData, bytes32 encodedDataHash) {
    require(tokens.length == cumulativeAmounts.length, 'bad tokens and amounts length');
    encodedData = abi.encode(cycle, index, account, tokens, cumulativeAmounts);
    encodedDataHash = keccak256(encodedData);
  }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

import "./IERC20.sol";
import "../../math/SafeMath.sol";
import "../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using SafeMath for uint256;
    using Address for address;

    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        // solhint-disable-next-line max-line-length
        require((value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).add(value);
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) { // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        uint256 c = a + b;
        if (c < a) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b > a) return (false, 0);
        return (true, a - b);
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) return (true, 0);
        uint256 c = a * b;
        if (c / a != b) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a / b);
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a % b);
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");
        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "SafeMath: subtraction overflow");
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) return 0;
        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");
        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: division by zero");
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: modulo by zero");
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        return a - b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryDiv}.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a % b;
    }
}

// SPDX-License-Identifier: MIT
pragma solidity 0.7.6;

import "./IERC20Ext.sol";


/**
 * @title Kyber utility file
 * mostly shared constants and rate calculation helpers
 * inherited by most of kyber contracts.
 * previous utils implementations are for previous solidity versions.
 */
abstract contract Utils {
    // Declared constants below to be used in tandem with
    // getDecimalsConstant(), for gas optimization purposes
    // which return decimals from a constant list of popular
    // tokens.
    IERC20Ext internal constant ETH_TOKEN_ADDRESS = IERC20Ext(
        0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE
    );
    IERC20Ext internal constant USDT_TOKEN_ADDRESS = IERC20Ext(
        0xdAC17F958D2ee523a2206206994597C13D831ec7
    );
    IERC20Ext internal constant DAI_TOKEN_ADDRESS = IERC20Ext(
        0x6B175474E89094C44Da98b954EedeAC495271d0F
    );
    IERC20Ext internal constant USDC_TOKEN_ADDRESS = IERC20Ext(
        0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48
    );
    IERC20Ext internal constant WBTC_TOKEN_ADDRESS = IERC20Ext(
        0x2260FAC5E5542a773Aa44fBCfeDf7C193bc2C599
    );
    IERC20Ext internal constant KNC_TOKEN_ADDRESS = IERC20Ext(
        0xdd974D5C2e2928deA5F71b9825b8b646686BD200
    );
    uint256 public constant BPS = 10000; // Basic Price Steps. 1 step = 0.01%
    uint256 internal constant PRECISION = (10**18);
    uint256 internal constant MAX_QTY = (10**28); // 10B tokens
    uint256 internal constant MAX_RATE = (PRECISION * 10**7); // up to 10M tokens per eth
    uint256 internal constant MAX_DECIMALS = 18;
    uint256 internal constant ETH_DECIMALS = 18;
    uint256 internal constant MAX_ALLOWANCE = uint256(-1); // token.approve inifinite

    mapping(IERC20Ext => uint256) internal decimals;

    /// @dev Sets the decimals of a token to storage if not already set, and returns
    ///      the decimals value of the token. Prefer using this function over
    ///      getDecimals(), to avoid forgetting to set decimals in local storage.
    /// @param token The token type
    /// @return tokenDecimals The decimals of the token
    function getSetDecimals(IERC20Ext token) internal returns (uint256 tokenDecimals) {
        tokenDecimals = getDecimalsConstant(token);
        if (tokenDecimals > 0) return tokenDecimals;

        tokenDecimals = decimals[token];
        if (tokenDecimals == 0) {
            tokenDecimals = token.decimals();
            decimals[token] = tokenDecimals;
        }
    }

    /// @dev Get the balance of a user
    /// @param token The token type
    /// @param user The user's address
    /// @return The balance
    function getBalance(IERC20Ext token, address user) internal view returns (uint256) {
        if (token == ETH_TOKEN_ADDRESS) {
            return user.balance;
        } else {
            return token.balanceOf(user);
        }
    }

    /// @dev Get the decimals of a token, read from the constant list, storage,
    ///      or from token.decimals(). Prefer using getSetDecimals when possible.
    /// @param token The token type
    /// @return tokenDecimals The decimals of the token
    function getDecimals(IERC20Ext token) internal view returns (uint256 tokenDecimals) {
        // return token decimals if has constant value
        tokenDecimals = getDecimalsConstant(token);
        if (tokenDecimals > 0) return tokenDecimals;

        // handle case where token decimals is not a declared decimal constant
        tokenDecimals = decimals[token];
        // moreover, very possible that old tokens have decimals 0
        // these tokens will just have higher gas fees.
        return (tokenDecimals > 0) ? tokenDecimals : token.decimals();
    }

    function calcDestAmount(
        IERC20Ext src,
        IERC20Ext dest,
        uint256 srcAmount,
        uint256 rate
    ) internal view returns (uint256) {
        return calcDstQty(srcAmount, getDecimals(src), getDecimals(dest), rate);
    }

    function calcSrcAmount(
        IERC20Ext src,
        IERC20Ext dest,
        uint256 destAmount,
        uint256 rate
    ) internal view returns (uint256) {
        return calcSrcQty(destAmount, getDecimals(src), getDecimals(dest), rate);
    }

    function calcDstQty(
        uint256 srcQty,
        uint256 srcDecimals,
        uint256 dstDecimals,
        uint256 rate
    ) internal pure returns (uint256) {
        require(srcQty <= MAX_QTY, "srcQty > MAX_QTY");
        require(rate <= MAX_RATE, "rate > MAX_RATE");

        if (dstDecimals >= srcDecimals) {
            require((dstDecimals - srcDecimals) <= MAX_DECIMALS, "dst - src > MAX_DECIMALS");
            return (srcQty * rate * (10**(dstDecimals - srcDecimals))) / PRECISION;
        } else {
            require((srcDecimals - dstDecimals) <= MAX_DECIMALS, "src - dst > MAX_DECIMALS");
            return (srcQty * rate) / (PRECISION * (10**(srcDecimals - dstDecimals)));
        }
    }

    function calcSrcQty(
        uint256 dstQty,
        uint256 srcDecimals,
        uint256 dstDecimals,
        uint256 rate
    ) internal pure returns (uint256) {
        require(dstQty <= MAX_QTY, "dstQty > MAX_QTY");
        require(rate <= MAX_RATE, "rate > MAX_RATE");

        //source quantity is rounded up. to avoid dest quantity being too low.
        uint256 numerator;
        uint256 denominator;
        if (srcDecimals >= dstDecimals) {
            require((srcDecimals - dstDecimals) <= MAX_DECIMALS, "src - dst > MAX_DECIMALS");
            numerator = (PRECISION * dstQty * (10**(srcDecimals - dstDecimals)));
            denominator = rate;
        } else {
            require((dstDecimals - srcDecimals) <= MAX_DECIMALS, "dst - src > MAX_DECIMALS");
            numerator = (PRECISION * dstQty);
            denominator = (rate * (10**(dstDecimals - srcDecimals)));
        }
        return (numerator + denominator - 1) / denominator; //avoid rounding down errors
    }

    function calcRateFromQty(
        uint256 srcAmount,
        uint256 destAmount,
        uint256 srcDecimals,
        uint256 dstDecimals
    ) internal pure returns (uint256) {
        require(srcAmount <= MAX_QTY, "srcAmount > MAX_QTY");
        require(destAmount <= MAX_QTY, "destAmount > MAX_QTY");

        if (dstDecimals >= srcDecimals) {
            require((dstDecimals - srcDecimals) <= MAX_DECIMALS, "dst - src > MAX_DECIMALS");
            return ((destAmount * PRECISION) / ((10**(dstDecimals - srcDecimals)) * srcAmount));
        } else {
            require((srcDecimals - dstDecimals) <= MAX_DECIMALS, "src - dst > MAX_DECIMALS");
            return ((destAmount * PRECISION * (10**(srcDecimals - dstDecimals))) / srcAmount);
        }
    }

    /// @dev save storage access by declaring token decimal constants
    /// @param token The token type
    /// @return token decimals
    function getDecimalsConstant(IERC20Ext token) internal pure returns (uint256) {
        if (token == ETH_TOKEN_ADDRESS) {
            return ETH_DECIMALS;
        } else if (token == USDT_TOKEN_ADDRESS) {
            return 6;
        } else if (token == DAI_TOKEN_ADDRESS) {
            return 18;
        } else if (token == USDC_TOKEN_ADDRESS) {
            return 6;
        } else if (token == WBTC_TOKEN_ADDRESS) {
            return 8;
        } else if (token == KNC_TOKEN_ADDRESS) {
            return 18;
        } else {
            return 0;
        }
    }

    function minOf(uint256 x, uint256 y) internal pure returns (uint256) {
        return x > y ? y : x;
    }
}

{
  "compilationTarget": {
    "contracts/reward/RewardsDistributor.sol": "RewardsDistributor"
  },
  "evmVersion": "istanbul",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": true,
    "runs": 1000
  },
  "remappings": []
}